Technological breakthrough in the development of powerful redox flow batteries
Fraunhofer UMSICHT researchers have developed a 3.2 m²-sized bipolar plate that allows for the construction of large scale redox flow batteries. Which role this technology can play in the energy transition will be on display at the ENERGY STORAGE 2017.
Electrical energy storage systems are key to the energy transition in order to stabilize the unsteady flow of power from wind power plants and solar cells commensurate with demand. Especially in case of high outputs (megawatts) and high capacities (megawatt hours), redox flow batteries provide for clear economic advantages. Unlike lithium cells, they can also be realized with very large cells. Therefore, the worldwide development is gearing towards larger cell areas.
Material successfully utilized
While the currently typical cell area corresponds more to that of a DIN A3 page, the long-term objective is to build cells and/or stacks that are 20-30 times that size. “Most of the components needed for a redox cell are already available or can already be produced at sufficiently large scale,” explained Prof. Christian Doetsch, Director of the Energy Division at Fraunhofer UMSICHT. “Until now, the bipolar plates constituted the bottleneck.” It is only with bipolar plates that the necessary stacks can be assembled from individual cells in order to subsequently configure them into a battery. Research regarding this issue is being carried out worldwide at high financial expenditure.
Fraunhofer UMSICHT developed a 3.2 m²-sized bipolar plate and produced it jointly with SAUERESSIG GmbH + Co. KG. To date, the plate is unique in its size and represents a key technology for large redox flow batteries. The novel bipolar plate material utilized has already today been utilized successfully in small redox flow stacks of the Fraunhofer start-up VOLTERION and tested in the field.
Providing 1,000 households with power for one day
The large area bipolar plate provides for an output per cell corresponding to approx. 5 kW (peak) and/or allows for approx. 350 kW (peak) as a stack with 70 cells. A redox flow system with three such stacks (1 MW, 10 MWh) can provide up to 1,000 households with power for one day. The capacity corresponds to approx. 2,000 typical PV lithium ion batteries (at 5 kWh, each). Additional decisive advantages of the new bipolar plate are the low minimum thickness (400-500 µm), the corresponding good conductivity, their flexibility, and the cost-efficient roll-to-roll production method.
The objective of Fraunhofer UMSICHT is to not only realize large stacks of its own with this novel bipolar plate, but to also engage – with industry partners – in a worldwide commercialization.
ENERGY STORAGE 2017, booth A07, hall 08B
From March 14-16, the ENERGY STORAGE EUROPE 2017 trade fair takes place in Düsseldorf, Germany. You can meet the experts of Fraunhofer UMSICHT on all days of the trade fair at booth A07, hall 08B. We are looking forward to your visit!
Our thanks go to the BMWi for its support of multiple sponsorship projects (incl. 03ET6077B) in the area of the redox flow battery – our previous work for this success would not have been possible without it.